In wireless networks, persistent scheduling takes advantage of the traffic characteristics of Voice over IP (VoIP) to increase the number of VoIP users in systems such as those conforming to the Institute for Electronic and Electrical Engineers (IEEE) 802.16 standard based WiMax, 3GPP LTE and 3GPP3 UMB systems. The periodic nature of the packet arrivals from a VoIP source allows the needed resource to be allocated persistently for the period of an active talk spurt. Consequently, base stations (BS) can send the allocation information once at the beginning of a talk spurt and avoid sending the allocation information anew for each subsequent packet. Significant resources that would otherwise be occupied by unnecessary overhead can now be used to accommodate VoIP packets from more users. Because VoIP packets are usually small in size, the savings from reduced overhead can significantly boost the overall system capacity. The capacity gain from persistent scheduling, however, can be compromised significantly due to dynamic link adaptation, which is a very common technique in wireless systems to adjust to dynamic variation in wireless channel quality.
Thus, a strong need exists for techniques for enhanced persistent scheduling with an efficient link adaptation capability.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.